EP3959497B1 - Method and device for measuring the local refractive power or refractive power distribution of a spectacle lens - Google Patents

Description

The invention relates to a method for measuring the local refractive power and/or the refractive power distribution of a left and/or a right spectacle lens, preferably in a spectacle frame. In addition, the invention relates to a computer program product with a computer program with program code and a device for carrying out the method.

In order to enable a spectacle wearer to see clearly, the spectacle lenses in the spectacle frame must be correctly positioned and aligned with the eyes of the spectacle wearer. Correct alignment and positioning is essential for all spectacle lenses. The correct alignment and positioning of the lenses is particularly important for individualized optical lens designs, for toric lens designs, for lenses with a high dioptric power and for varifocal lenses. Varifocal lenses enable spectacle wearers to see clearly in different usage situations, e.g. B. at different distances, just by changing the line of sight, without the need for greater accommodation success of the eyes. According to DIN EN ISO 13666:2013-10, paragraph 8.3.5, progressive lenses are lenses with at least one progressive surface and an increasing (positive) dioptric power when the wearer looks down. Customized lenses and/or varifocal lenses have one or more reference points, e.g. B. a far visual point and / or a near visual point, the position of which must be adjusted depending on the use situation to the location of the pupils of the eyes of a spectacle wearer. According to DIN EN ISO 13666:2013-10, paragraph 5.16, the far visual point is the assumed position of the visual point on a spectacle lens for distance vision under certain conditions. The near visual point is according to DIN EN ISO 13666:2013-10, paragraph 5.17, the assumed location of the visual point on a lens for near vision under certain conditions. Additionally, with toric lens designs, there is a need for the correct orientation of their cylindrical power for a wearer.

From the WO 2016/207412 A1 a method and a device of the type mentioned is known. There, the measurement of the local refractive power of a left and/or right spectacle lens in a spectacle frame is described using a measuring device in which the spectacle frame is arranged. This measuring device contains an image acquisition device and a display for showing a test structure whose position relative to the image acquisition device is known. The test structure displayed on the display is captured by the image capturing device with an imaging beam path that passes through the left and/or the right spectacle lens in the spectacle frame. In addition, a section of the spectacle frame that defines a coordinate system of the spectacle frame is recorded by means of the display. In a computer unit, the local refractive power of a left and/or right spectacle lens is then determined by image processing from the detected section of the spectacle frame and the detected image of the test structure and from the coordinates of the test structure and the detected image of the test structure in a coordinate system referenced to the coordinate system of the spectacle frame definitely.

the EP 2 608 109 A1 discloses a method for determining a refractive power of a spectacle lens in the wearing position. A recording of the spectacle wearer without a spectacle frame and a recording of the spectacle wearer with a spectacle frame are recorded and the size of the iris is determined in both recordings. The refractive power of the lens is determined from the difference in size and the focal length of the camera. For this procedure it is necessary that the glasses are worn by the glasses wearer. In addition, this method allows no local determination of the refractive power at individual points on the lens and determination of the individual beam paths through the lens.

the U.S. 2015/0362998 A1 and the US 10,019,140 B1 each describe methods of determining the distance of a person's face from an image capture device capturing that face using photogrammetry.

From the WO 2016/076530 A1 a method for measuring the refractive power of spectacles is known, in which the refractive power of the lens is deduced from the difference in size of an object between a photograph taken without a spectacle lens and a photograph taken through the spectacle lens.

the WO 2017/134275 A1 describes the measurement of the local refractive power of a left and/or a right spectacle lens in a spectacle frame by evaluating at least one image of a left and/or right spectacle lens in a spectacle frame, which is captured against a background whose geometry is either known or estimated. The method requires knowledge of the camera recording position in order to be able to specify the optical axis of the left and/or right spectacle lens in a spectacle frame or a local spectacle lens refractive power. No coordinates of points on the background in front of which the spectacle lens to be measured is arranged are calculated here.

the US 2015/0029323 A1 describes an image processing device with a memory and with a processor coupled to the memory, which is used to determine the optical properties of glasses by evaluating images of the glasses wearer, which are captured by an image acquisition device and which show the glasses wearer with and without glasses. In the US 2015/0029323 A1 is specified based on the spatial position of a facial contour of the face detected through glasses with spectacle lenses of a glasses wearer and the spatial position of a detected facial contour of this face glasses to close the refractive power of a lens in the glasses.

The object of the invention is to determine the focusing or the dioptric effect of a left and/or a right spectacle lens for distance and/or for near in a simple manner and without great expense in terms of apparatus. In particular, it is an object of the invention to determine a local refractive power at different points on a spectacle lens, i. H. a refractive power distribution to be determined with a high degree of accuracy.

This object is achieved by the method specified in claim 1 and claim 2. Advantageous developments of the invention are specified in the dependent claims.

In the method specified in claim 1 for measuring the local refractive power and/or the refractive power distribution of a left and/or a right spectacle lens in a spectacle frame, at least one first image of a scene from at least one first recording position is captured in a first step by means of at least one image capturing device. this at least one first image having at least one structural point and containing a left and/or a right spectacle lens in a spectacle frame, the at least one imaging beam path for each of these structural points passing through the first or the second spectacle lens of the spectacle frame.

This invention understands refractive power to mean the focusing effect or the dioptric effect or of a spectacle lens. According to the definition given in DIN EN ISO 13666:2013-10, paragraph 9.2, the focussing effect is understood by this invention as the collective term for the spherical and astigmatic effect of a spectacle lens. This invention understands the dioptric power of a spectacle lens to correspond to that in DIN EN ISO 13666:2013-10, paragraph 9.3, the collective term for the focusing and the prismatic effect of the lens. In accordance with the definition given in DIN EN ISO 13666:2013-10, paragraph 10.9, the invention understands the prismatic effect of a spectacle lens to be the collective term for prismatic deflection and base position.

This invention understands local refractive power to mean the local focusing effect or the local dioptric effect of a spectacle lens.

This invention understands refractive power distribution to mean the spatially resolved focusing effect or the spatially resolved dioptric effect of a spectacle lens.

The invention understands a scene to be a section of an environment that is captured by at least one image acquisition device, e.g. B. can be detected with at least one digital camera, which is integrated, for example, in a smartphone or in a tablet computer. For example, a scene can B. be a section of a room in an apartment or a section of a shop or part of a landscape. However, a scene can also contain a face or only a left eye and/or a right eye of a person wearing the glasses.

At least one structure point of a scene is understood here as a geometric point whose image in at least one image or recording of the scene by capturing the scene with at least one image acquisition device due to a brightness and/or color of an image of this point that differs from the image of this point neighboring points can be clearly seen. A structure point can e.g. B. at a corner or edge of a structure in the scene.

In the present case, however, the term structure point of a scene also includes a point in a stationary, time-invariant pattern, e.g. B. at least one Dot in a regular or irregular dot pattern, at least one dot in a regular or irregular stripe pattern, at least one dot in a regular or irregular checkered pattern, at least one dot in a barcode, at least one dot in a 2D code and/or at least one dot within a written text, for example a newspaper or a book, or an electronic display device, for example a screen. In particular, at least one stationary, time-invariant structure point in a scene can be at least one point on a structured surface, for example a structured tablecloth or on structured wallpaper.

However, the term structural point of a scene is also understood to mean at least one point in a scene whose position can change over time, e.g. B. at least one point on the face of a spectacle wearer that moves, such as a point on eyebrows, on lips or a point lying on the iris. If the position of the at least one structure point in a scene changes over time, its displacement is preferably reconstructed as far as possible and then taken into account when determining the local refractive power of a left and/or right spectacle lens. In the event that the displacement of such a structure point cannot be reconstructed, it is advantageous if this structure point is not taken into account when determining the local refractive power and/or the refractive power distribution of a left and/or right spectacle lens.

The invention preferably understands at least one image acquisition device to be a digital camera which, e.g. B. is integrated in a mobile terminal such as a mobile phone, a smartphone or a tablet computer. The digital camera can be designed as a stereo camera, as a multi-camera, as an image sensor with one lens or as an image sensor with at least two lenses and/or as a so-called plenoptic camera. It should be noted that a mobile terminal specified standing also may have several image acquisition devices in the form of a digital camera.

A mobile terminal device is to be understood in particular as a device which comprises at least one programmable processor and at least one image acquisition device, e.g. at least one camera, and at least one acceleration sensor, and which is preferably designed to be carried, i.e. designed in such a way in terms of dimensions and weight is that it can be carried by one person. Additional components can be present in the mobile end device, such as at least one screen, at least one light source for, for example, visible light in a wavelength range from 380 nm to 780 nm and/or infrared light in a wavelength range from 780 nm to 1 mm and/or at least one light receiver with a sensitivity for, for example, visible light in a wavelength range from 380 nm to 780 nm and/or infrared light in a wavelength range from >780 nm to 1 mm. Typical examples of such mobile devices are smartphones or tablet PCs, which have at least one screen, for example a touch screen, at least one image acquisition device, e.g. at least one camera, at least one acceleration sensor, at least one light source, at least one light receiver and other components such as wireless interfaces for mobile communications or WLAN (wireless LAN) may have.

In the present case, an imaging beam path for a structure point is understood to mean the path of the light rays that cause an optical imaging of the structure point from the scene as a structure point image in the image of the scene in at least one image acquisition device. In the following, its optical axis, which forms an axis of symmetry, is referred to as the chief ray of the imaging beam path for a structure point.

In the method specified in claim 1, in a further step, which can take place before or after the first step or at the same time as the first, at least two further images of the scene without the first and/or the second lens of the spectacle frame or without the Spectacle frames containing the first and/or the second lens with the structure points shown in the first image are captured by means of at least one image capturing device from at least two different recording positions, wherein at least one of the recording positions can be identical to the at least one first recording position. In the further step, the at least one image acquisition device can be identical to or different from the at least one image acquisition device from the first step. The at least one image acquisition device in the further step is preferably identical to the at least one image acquisition device from the first step. Then, in a calculation step, the coordinates of the structure points are determined in a coordinate system from the at least two further images of the scene by means of image evaluation, preferably by means of triangulation. The local refractive power is then determined in a step of determining a local refractive power for at least a section of the left lens and/or a section of the right lens from the coordinates of the structure points and the image of the structure points in the at least one first image of the scene.

The method specified in claim 2 for measuring the local refractive power and/or the refractive power distribution of a left and/or a right spectacle lens in a spectacle frame provides, in a first step, at least one image of a scene from at least one first recording position by means of at least one image acquisition device detect, this at least one first image having at least one structural point and containing a left and/or a right spectacle lens in a spectacle frame, the at least one imaging beam path for each of these Structural points penetrates the first or the second lens of the spectacle frame.

As stated above, the imaging beam path for a structure point is understood to be the course of the light rays that cause an optical imaging of the structure point from the scene as a structure point image in the image of the scene captured by at least one image acquisition device. In the following, its optical axis, which forms an axis of symmetry, is referred to as the chief ray of the imaging beam path for a structure point.

In a further step, which can be before or after the first step or which can take place at the same time as the first step, at least two further images of the scene with the left and/or the right spectacle lens are created in a spectacle frame by means of at least one image acquisition device from at least two different further recording positions different from the first recording position, each with at least one imaging beam path for the structure points shown in the first image, this at least one imaging beam path not penetrating the first and the second spectacle lens of the spectacle frame. In a further step, the coordinates of the structure points are calculated in a coordinate system from the respective at least one beam path of the structure points that have not penetrated the left and right spectacle lens by means of image evaluation, preferably by means of triangulation. The local refractive power for at least one section of the left lens and/or for at least one section of the right lens is then determined from the coordinates of the structure points and the image of the structure points in the at least one first image of the scene.

In an advantageous development of an above-specified method for measuring the local refractive power and/or refractive power distribution of a left and/or a right spectacle lens, preferably in a spectacle frame, a large number of structure points in a scene from at least one first recording position are each recorded in a first image of the scene is recorded and the steps following the recording are carried out on the basis of this respective multiplicity of structure points.

In the present case, a multiplicity of structure points is understood to mean a set of points consisting of at least three structure points. It is advantageous if the local refractive power of a left and/or a right spectacle lens is measured using at least 10, preferably at least 100, particularly preferably at least 1000 and very particularly preferably at least 10000 structure points. It is favorable if the local refractive power of a left and/or right spectacle lens is measured using a number Z of structure points for which the following applies: 100≦Z≦1000.

By measuring the local refractive power at a large number of different points on the left and/or right spectacle lens, it is possible to determine a refractive power distribution for the left and/or right spectacle lens.

The image evaluation of each image preferably includes image processing technologies such as classification, segmentation and triangulation. With the help of methods for object recognition, such as segmentation and classification, each image is preferably examined for objects of the scene and/or eyeglass frame classes. The methods for object recognition can be of a classical nature, such as thresholding, edge- or region-based segmentation, optical flow, or of a learning nature. If the methods for object recognition are of a learning nature, such as when using learning algorithms, it is necessary to train a neural network with augmented training data in advance. The result of each of these object recognition methods is the position, location and boundary of the objects, here the scene and/or spectacle frame classes. Additional information is the existence of the respective objects in the respective images. In this way, for example, it can be recognized whether a spectacle frame and/or a spectacle lens is/are present in the image or not. Thus, the assignment as to whether it is a first or a further image can also take place after it has been recorded. The assignment as to whether it is a first or a second image can continue to be made without knowing whether it was a first or a further image.

In the methods specified above, the structure points can each only be stationary or each both stationary and time-invariant. Alternatively, the displacement of the at least one structure point can be known in each case and/or its displacement can be reconstructed and taken into account when determining the refractive power distribution. The structure points are preferably each stationary, particularly preferably each stationary and time-invariant.

From the refractive power distribution of a left and/or right spectacle lens or at least a section of a left and/or right spectacle lens determined in one of the methods described above, conclusions can be drawn about the local refractive power at a specific point of the spectacle lens.

In the above-mentioned methods, in the first step in each case, in which at least one image of a scene from at least one first recording position is captured by means of at least one image capturing device, the edge or the edge curve of the left and/or right spectacle lens in a spectacle frame can optionally be captured .

The edge curve is preferably the shape-determining boundary of the spectacle lens lying in the front surface of the spectacle frame facing away from the face, which partially or completely coincides with the front inner edge of the spectacle frame in half-rimmed or full-rimmed spectacles. In the case of full-rim glasses, the edge curve on the front surface of the frame facing away from the face is equal to the outer edge of the lens on the front or the inner edge of the frame on the front. In the case of half-rimmed spectacles, the edge curve on the front surface of the spectacle frame facing away from the face is the same as the outer edge of the lens on the front or the inner edge of the frame on the front, insofar as there is a structure given by the frame. If there is no structure given by the frame in the case of half-rimmed glasses, the edge curve on the front surface of the glasses frame facing away from the face is the same as the outer edge of the glass on the front side. With frameless glasses there is no analogous structure of the frame, i.e. the term edge curve here always refers to the front outer edge of the glass in the front surface of the glasses frame facing away from the face.

If an image acquisition device arranged in a mobile terminal is used in the method specified in claim 1, which contains at least two digital cameras, a stereo camera, a multi-camera, a camera chip with at least two lenses or a plenoptic camera, it may be sufficient to use a single image of the scene with the spectacle frame containing the first and/or the second spectacle lens, this one first image having at least one structure point, and a single further image of the scene without the spectacle frame containing the first and/or the second spectacle lens with the same structure points to capture the first image of a scene. To increase the accuracy of the method according to claim 1, at least two images of the scene with the spectacle frame containing the first and/or the second spectacle lens and at least two images of the scene without the spectacle frame containing the first and/or the second spectacle lens are preferably recorded.

If an image acquisition device arranged in a mobile terminal is used in the method specified in claim 2, which contains at least two digital cameras, a stereo camera, a multi-camera, a camera chip with at least two lenses or a plenoptic camera, it may be sufficient to use a single image the scene with the spectacle frame containing the first and/or the second spectacle lens, with this first image having at least one structural point, with the at least one imaging beam path passing through the first and/or the second spectacle lens for each of these structural points, and a single further image Image of the scene with the spectacle frame containing the first and/or the second spectacle lens, whereby this at least one further image is recorded from a recording position that differs from the first recording position, so that the at least one imaging beam path for each of these structures points do not penetrate the first and the second lens of the spectacle frame. In this embodiment of the method as claimed in claim 2, at least two first images with the spectacle frame and at least two further images of the scene with the spectacle frame are preferably created from shooting positions different from the first two shooting positions in order to increase its accuracy.

For the measurement of spectacle lenses with a strongly negative refractive power, ie with a principal meridian with a negative refractive power less than or equal to -3 dpt, it is advantageous if the scene for determining the local refractive power and/or the refractive power distribution has a left and/or right Spectacle lens, each preferably in a spectacle frame, contains at least one structural point, preferably at least one stationary, time-invariant structural point, which is detected through a left and/or right spectacle lens and which has a distance from the spectacle lens to be measured in each case that is preferably between 5 mm and 200 mm.

The distance of a structure point from a spectacle lens is understood here to be the distance of the structure point to the penetration point of the main ray of the imaging beam path on the side of the spectacle lens facing the structure point. It should be noted that by capturing further images of the scene from other, different recording positions, it is fundamentally possible to specify the main ray for an optical image in the image capturing device for each structure point in the distance range specified above.

For measuring spectacle lenses with a strongly positive refractive power, i. H. with a main section with a positive refractive power greater than or equal to +3 dpt, it is advantageous if the scene for determining the local refractive power and/or the refractive power distribution of a left and/or right spectacle lens, preferably in a spectacle frame, has at least one structure point, preferably contains at least one fixed, time-invariant structure point, which is detected through a left and/or right spectacle lens and which is at a distance from the spectacle lens to be measured in each case, which is preferably in front of the focal point of the stronger principal meridian. This distance is preferably between 5 mm and 100 mm.

For measuring spectacle lenses with low refractive power, i. i.e., with a principal meridian with a negative refractive power less than -3 dpt or with a principal meridian with a positive refractive power greater than +3 dpt, good measurement results are achieved in scenes with at least one structure point, preferably at least one stationary, time-invariant structure point, whose distance from the each spectacle lens to be measured, preferably in a spectacle frame, is up to 600 mm, preferably in a range from 5 mm to 500 mm.

One finding of the invention is in particular that the local refractive power and/or refractive power distribution of a spectacle lens with the lens according to the invention Method can be determined very precisely if the distance from at least one structure point, preferably at least one stationary, time-invariant structure point, in a scene from a spectacle lens in a spectacle frame is between 10 mm and 50 mm, preferably between 30 mm and 40 mm.

An advantageous embodiment of the invention provides that a large number of first images of the scene and a large number of further images of the scene are recorded, each including the spectacle lens whose local refractive power and/or refractive power distribution is to be determined, with this spectacle lens preferably being located in a spectacle frame . Alternatively, the spectacle frame can also be removed from the scene when recording the large number of further images. For capturing a large number of first images of the scene and a large number of further images of the scene, it is advantageous if these span at least part of a hemisphere or a hemisphere around the scene and/or a large number of different recording positions with different recording directions and/or Cover recording distances. This is because the coordinates of the at least one structure point can then be calculated from the large number of further images of the scene.

A correspondingly large number of captured first images of the scene and captured additional images of the scene increase the accuracy of the method for measuring the local refractive power and/or the refractive power distribution of a left and/or a right spectacle lens, preferably in a spectacle frame.

By using the image capturing device to capture a large number of images of the scene, in particular the head, by displacing the at least one image capturing device or, in the case of a stationary image capturing device, by rotating the scene, in particular the head, with the left eye and/or the right eye of the spectacle wearer being glasses frame too of the relocated image capturing device and from the large number of images of the scene recorded in the process, in particular of the head, through-lens optical paths for different directions of vision of the left eye and/or right eye of the spectacle wearer of the spectacle frame through the left spectacle lens and/or the right spectacle lens are calculated and for a each viewing direction a local refractive power k(x, y) of the left spectacle lens and/or the right spectacle lens is determined, it is possible to determine the local refractive power of the spectacle lenses in the spectacle frame worn by the spectacle wearer for a viewing direction selected by a spectacle wearer.

The measurement of the local refractive power and/or the distribution of the refractive power of a left and a right spectacle lens in a spectacle frame allows, in particular, statements to be made about the so-called binocular effects of spectacles, i. H. a frame including both lenses. A binocular effect is the assessment of the focusing or dioptric effect of the left and right spectacle lens for a specific viewing direction. A binocular effect can also cause aberrations of the spectacle lens that are of a higher order, such as e.g. B. coma, or prismatic errors include.

The measurement of the local refractive power and/or the distribution of the refractive power of a left and a right spectacle lens in a spectacle frame makes it possible to determine whether, in a certain viewing direction, e.g. B. the astigmatic power comprising the difference in the refractive power in the main sections and their direction, of the spectacle lens deviates significantly from the binocular target values. The binocular target values are the subjectively determined refraction, including sphere, cylinder with axis and prism with base position, of both eyes. For the spectacle wearer, a deviation from the binocular target values is not or only slightly noticeable if e.g. B. the deviation of the astigmatic power of the left and right spectacle lens from the binocular target values is the same. For the spectacle wearer, however, this deviation from the binocular target values is clearly noticeable when the deviation of the astigmatic power of the left and right spectacle lenses from the binocular target values is different.

It should be noted that an incorrect prismatic effect between the right and left spectacle lens is perceived as very unpleasant by a spectacle wearer. In this case, an incorrect nasal prismatic effect is more readily accepted by a spectacle wearer than an incorrect temporal prismatic effect and/or an incorrect vertical prismatic effect.

The method specified above offers the particular advantage that the deviation of the prismatic power of the left spectacle lens and the right spectacle lens from a binocular target value in a wearing situation can be determined by simultaneously measuring a right and a left spectacle lens in a spectacle frame.

An advantageous embodiment of the invention provides that the coordinates of the structure points are calculated by evaluating shifts in the images of the structure points in the scene in the recordings from different recording positions in a coordinate system. Methods for feature detection, so-called "feature detection methods" can be used, e.g. B. gradient-based feature descriptors such as SIFT and SURF features or binary feature descriptors such as BRIEF or BRISK features, as z. B. in the article "A comparison of feature descriptors for visual SLAM" by J. Hartmann, J. Klüssendorff and Erik Maehle, European Conference on Mobile Robots 2013 are described, to which reference is hereby made in full and its disclosure in the description of this invention is included.

The coordinates of the structural points can be related to any fixed coordinate system, in particular to a coordinate system defined by the at least one image acquisition device during a recording position. Preferably, this coordinate system is referenced to the eyeglass frame coordinate system, which may be defined by a portion of the eyeglass frame. Two mutually referenced coordinate systems are understood to be coordinate systems for which it is known what the coordinates of a point or vector are from one coordinate system in the other coordinate system. In particular, by determining the distances between the coordinates of the structure points, it can be achieved that scenes with changes over time, such as e.g. B. the face of a spectacle wearer, the local refractive power and / or the refractive power distribution of a left and / or right lens in a spectacle frame can be determined.

In a further advantageous embodiment of the invention, it is provided that by evaluating neighboring relationships between the structure points in the scene, a displacement of at least one structure point in a coordinate system is recognized and the coordinates of at least one structure point displaced in a scene when determining the local refractive power and/or or refractive power distribution for at least a portion of the right spectacle lens and/or the left spectacle lens is not taken into account in the coordinate system of the spectacle frame. In this way it can be achieved that movements of structural points in a scene have no influence on the measurement result for the local refractive power and/or refractive power distribution of a left and/or right spectacle lens in a spectacle frame and do not falsify the measurement result.

The invention is based in particular on the idea that the recording of a large number of images of a scene, in particular the recording of a film or video sequence of a scene, with at least one image acquisition device from different recording positions and/or recording directions, the calculation of so-called intrinsic parameters of the at least one Image acquisition device and its spatial position in relation to the scene by means of image processing z. B. using SLAM algorithms, i.e. algorithms for simultaneous localization and mapping (Simultaneous Localization and Mapping), as described in the publication " A. Teichmann et al., Unsupervised intrinsic calibration of depth sensors via SLAM, Robotics: Science and Systems 2013, Berlin Germany, June 24 - 28, 2013 " is described, to which reference is hereby made in full and the disclosure of which is included in the description of this invention, if the scene contains characteristic structural features with at least one structural point. It is advantageous here if the scene has characteristic structural features with a large number of clearly defined, preferably stationary, time-invariant structure points.Such characteristic structure features can be, for example, brightness gradients on objects with, for example, an intersection of two edge lines, characteristic colors of objects or also characteristic geometric shapes of objects.

zusammengefasst. Im Rahmen der Erfindung können intrinsische Parameter einer Kamera auch Verzerrungsparameter sein, die zur Bestimmung von Bildverzerrungen, insbesondere der radialen und tangentialen Verzerrung, dienen. Die intrinsischen Parameter einer Bilderfassungseinrichtung beschreiben, wie eine 3D-Koordinate eines Objektpunkts in eine Bildebene der Bilderfassungseirichtung abgebildet wird bzw. wie aus einem gegebenen Punkt auf der Bildebene der zugehörige Strahlengang in einem zu der Bilderfassungseinrichtung ortsfesten Koordinatensystem berechnet werden kann.Intrinsic parameters of an image capturing device mean the focal length f of a camera in the image capturing device, the coordinates of the image center Z _x and Z _y , the shear parameter s and the scaling parameters m _x and m _y due to differently scaled coordinate axes of the image plane. These parameters are used in a camera calibration operator $$\bar{K}=\left(\begin{array}{ccc}f\cdot m_x& s& Z_x\cdot m_x\\ 0& f\cdot m_y& Z_y\cdot m_y\\ 0& 0& 1\end{array}\right)$$

summarized. Within the scope of the invention, intrinsic parameters of a camera can also be distortion parameters, which are used to determine image distortions, in particular radial and tangential distortion. The intrinsic parameters of an image capturing device describe how a 3D coordinate of an object point is mapped into an image plane of the image capturing device or how from a given point the image plane, the associated beam path can be calculated in a coordinate system that is stationary with respect to the image acquisition device.

mit $$\mathit{det}\bar{R}=1,$$

der die Rotation der Kamera um das Zentrum des Koordinatensystems festlegt, und einen Translationsvektor $$\overrightarrow{T}=\left(\begin{array}{c}{t}_1\\ t_2\\ t_3\end{array}\right),$$

der die Verschiebung des Kamerazentrums relativ zu dem Ursprung des Koordinatensystems festlegt, beschrieben. Eine Koordinate c in diesem Koordinatensystem wird durch die Abbildungsvorschrift $$f\left(c\right)=\bar{K}\cdot \left(\bar{R}\cdot c+\bar{T}\right)$$

und der Berechnung der zugehörigen zwei-dimensionalen inhomogenen Koordinaten mittels Division des Ergebnisvektors durch seine dritte Koordinate auf die entsprechenden 2D-Koordinaten auf der Bildebene der Kamera abgebildet.The position of an image acquisition device with respect to a coordinate system in space is determined by a rotation operator $$\bar{R}=\left(\begin{array}{ccc}{R}_{11}& R_{12}& R_{13}\\ R_{21}& R_{22}& R_{23}\\ R_{31}& R_{32}& R_{33}\end{array}\right)$$

With $$\mathit{de}\bar{R}=1,$$

which defines the rotation of the camera around the center of the coordinate system, and a translation vector $$\overrightarrow{T}=\left(\begin{array}{c}{t}_1\\ t_2\\ t_3\end{array}\right),$$

which specifies the displacement of the camera center relative to the origin of the coordinate system. A coordinate c in this coordinate system is determined by the mapping rule $$f\left(c\right)=\bar{K}\cdot \left(\bar{R}\cdot c+\bar{T}\right)$$

and calculating the associated two-dimensional inhomogeneous coordinates by dividing the result vector by its third coordinate onto the corresponding 2D coordinates on the image plane of the camera.

der zugehörige Lichtstrahl bestimmt werden, der auf diese Koordinate abgebildet wird.Conversely, a two-dimensional pixel coordinate y in homogeneous coordinates on the image plane of the camera can be obtained using the mapping rule $$G\left(y\right)={\bar{R}}^T\cdot \left({\bar{K}}^{-1}\cdot y-\bar{T}\right)$$

the associated light beam can be determined, which is imaged on this coordinate.

This is in detail in the book " Multiple View Geometry" by R. Hartley and A. Zisserman, Cambridge University Press 2004, pages 153 to 193 , shown, to which reference is hereby made in its entirety and the disclosure of which is included in the description of this invention.

From the large number of images of a scene, the information of a 3D model of the scene without the glasses frame, the information about the position and location of the glasses frame in the scene and the information about the position of the at least one image capturing device in the scene are then recorded for each individual picture, i.e. H. determined for each point in time of a recording. From this, beam paths through the spectacle lenses are then determined in order to then use these to calculate the local refractive power and/or refractive power distribution of the left and/or right spectacle lens.

An advantageous development of the invention therefore provides that a SLAM algorithm is used to calculate the coordinates of the at least one structure point. In this way, the accuracy of the calculation of the coordinates and the positions of the image acquisition devices can be increased and the computing effort for determining the coordinates of at least one structure point in a scene can be minimized and the computing time required for this can therefore be kept low.

In particular, a SLAM algorithm makes it possible to calculate both a three-dimensional geometry of the scene and the positions of the at least one image acquisition device from images of one and the same scene, which are captured from different recording positions and which therefore show the scene from different perspectives in capturing images of the scene. A SLAM algorithm comprises a feature recognition routine that detects features present in the scene, and an adjustment routine (matching routine) by means of which the corresponding feature in the images recorded from different recording positions is recognized for each feature in a recording. A three-dimensional model of the scene is then created from the corresponding positions of each feature in the image recordings using the intrinsic parameters of the at least one image recording device and the spatial positions of the image recording devices belonging to the recordings.

A computer program product according to the invention contains a computer program with program code for carrying out the method steps specified above when the computer program is loaded into a computer unit and/or executed in a computer unit.

A device according to the invention for measuring the local refractive power and/or the refractive power distribution of a left and/or a right spectacle lens in a spectacle frame contains at least one image acquisition device and a computer unit into which a computer program with program code for carrying out the method steps specified above is loaded.

Such a device can be designed in particular as a smartphone or as a tablet computer or as a digital camera. Advantageous exemplary embodiments of the invention, which are shown schematically in the drawings, are described below.

The accuracy of a SLAM algorithm, which determines both the position and/or location of the at least one image acquisition device and the position of the structure points in the image, is preferably determined by the calibration of the at least one image acquisition device used. Such a calibration is capable of each pixel coordinate C of to assign a three-dimensional light beam incident in the respective image acquisition device to at least one image acquisition device. Such a calibration can be expressed mathematically as an intrinsic camera calibration operator K̅ , which contains the intrinsic parameters described above. This camera calibration operator K̅ can e.g. B. from a recording of a special calibration pattern, z. B. a checkerboard pattern or a dot pattern can be determined by means of the at least one image acquisition device. As an alternative to this, it is also possible to determine the intrinsic camera calibration operator K - directly from the plurality of images of the scene, which can be based on different recording positions, by evaluating a large number of images of at least one scene.

By means of the calibration described above, the SLAM algorithm can assign each structural point to a multiplicity of three-dimensional light beams which are incident on the respective image acquisition device and do not pass through the left and right spectacle lens. The coordinates of the structure points in space can then be determined from these. From these coordinates in space and the recordings of the structure points, which were observed through the right and/or left spectacle lens by the at least one recording unit, a large number of imaging beam paths can be determined which pass through the right and/or left spectacle lens and after refraction through the right and/or left lens reach the respective known structural point. This ray model spanned in this way is preferably used in order to determine the dioptric power or the local refractive power or the refractive power distribution of the left and/or right spectacle lens.

In the case of a regular pattern, recording the scene also captures its periodicity. In a further embodiment of the invention, from the interpretation of the local direction-dependent enlargement or the local direction-dependent reduction of the pattern the local focusing effect of at least the right and/or left spectacle lens can be inferred. According to DIN EN ISO 13666:2013-10, paragraph 9.2, the focusing effect is the collective term for the spherical and astigmatic effect of a spectacle lens. The local focusing effect can thus be determined, for example, in a targeted manner at the far visual point and/or at the near visual point. Alternatively, by determining the local focusing effect at several points on the spectacle lens, conclusions can be drawn about its refractive power distribution.

1. a) Darstellen eines Zeichens auf einem Bildschirm, wobei ein Parameter des auf dem Bildschirm dargestellten Zeichens verändert wird;
2. b) Erfassen einer Augenbewegungsmetrik des Auges des Nutzers in Abhängigkeit von dem auf dem Bildschirm dargestellten Zeichen; und
3. c) Feststellen eines Zeitpunkts, zu dem sich aus der Augenbewegungsmetrik des Auges des Nutzers eine Erkennungsschwelle des Nutzers für das auf dem Bildschirm dargestellte Zeichen ergibt; und
4. d) Bestimmen eines Wertes für den Refraktionsfehler des Auges des Nutzers aus dem zu dem Zeitpunkt festgelegten Parameter.

In another aspect, the method described above can be used in conjunction with at least one other method. This at least one further method can be, for example, a method for determining a refractive error in an eye of a user, preferably a method according to EP 19 170 561.5 , which method comprises the following steps:

1. a) displaying a character on a screen, wherein a parameter of the character displayed on the screen is changed;
2. b) acquiring an eye movement metric of the user's eye as a function of the character displayed on the screen; and
3. c) determining a point in time at which a recognition threshold for the user for the character displayed on the screen results from the eye movement metric of the user's eye; and
4. d) determining a value for the refractive error of the user's eye from the parameter set at the time.

1. a) Aufnehmen eines Bildes unter Verwendung eines Brillenglases; und
2. b) Ermitteln mindestens eines optischen Parameters des Brillenglases mittels Bildverarbeitung des Bildes, wobei das Bild eine die Augen einschließende Augenpartie und/oder eine an die Augen angrenzende Gesichtspartie eines Nutzers des Brillenglases umfasst.

Alternatively or in addition to the method described above, the at least one further method can also be, for example, a method for determining at least one optical parameter of a spectacle lens, preferably a method according to the European patent application with the application file number EP19170551.6 this method comprising the following steps:

1. a) taking an image using a spectacle lens; and
2. b) Determining at least one optical parameter of the spectacle lens by means of image processing of the image, the image comprising an eye area enclosing the eyes and/or a facial area of a user of the spectacle lens adjoining the eyes.

1. a) Darstellen eines Zeichens auf einem Bildschirm, wobei ein Parameter des auf dem Bildschirm dargestellten Zeichens verändert wird;
2. b) Erfassen einer Reaktion des Nutzers in Abhängigkeit von dem auf dem Bildschirm dargestellten Zeichen;
3. c) Feststellen eines Zeitpunkts, zu dem sich aus der Reaktion des Nutzers eine Erkennbarkeit des auf dem Bildschirm dargestellten Zeichens für den Nutzer ergibt; und
4. d) Bestimmen eines Wertes für den Refraktionsfehler des Auges des Nutzers aus dem zu dem Zeitpunkt festgelegten Parameter, wobei das auf dem Bildschirm dargestellte Zeichen ein periodisches Muster ist, wobei der Parameter des auf dem Bildschirm dargestellten Musters mindestens eine Ortsfrequenz umfasst, und der Wert für den Refraktionsfehler aus der zu dem Zeitpunkt festgelegten Ortsfrequenz des Musters bestimmt wird.

As an alternative or in addition to the methods described above, the at least one additional method can also be a method for determining a refractive error in a user's eye, preferably a method according to the European patent application with the application reference number EP19170558.1 this method comprising the following steps:

1. a) displaying a character on a screen, wherein a parameter of the character displayed on the screen is changed;
2. b) detecting a reaction of the user depending on the character displayed on the screen;
3. c) determination of a point in time at which the user's reaction results in recognizability of the character displayed on the screen for the user; and
4. d) determining a value for the refractive error of the user's eye from the parameter set at the time, the character displayed on the screen being a periodic pattern, the parameter of the pattern displayed on the screen comprising at least one spatial frequency, and the value for the refractive error is determined from the spatial frequency of the pattern determined at the time.

As an alternative or in addition to the methods described above, a method for determining the refractive power distribution of a spectacle lens is also possible as at least one additional method, preferably a method according to the European patent application with the application file number EP19170714.0 , which enables a local refractive power from the size and/or shape comparison of the image of the anterior segment of the eye for a specific viewing direction. At least one recording is required for this of the anterior segment of the eye with and without the lens in front of it and comparing the recording with and without the lens.

In a higher-level application, the various methods described above, i. H. the method according to the invention and the at least one further method, can be combined in order, for example, to obtain greater accuracy or a plausibility check of the results obtained in the individual methods from a comparison of the results obtained in each case. The various methods described above can be performed sequentially or simultaneously in the parent application. If the various methods occur sequentially, their order may be independent of one another and/or any order. If the various methods are carried out one after the other, it may be preferable to carry out at least one of the methods according to the invention for determining the refractive power distribution last. A higher-level application can, for example, be a computer program that includes the various methods.

Fig. 1

eine Szene mit einer Brillenfassung und mit einer Bilderfassungs-einrichtung, die in unterschiedlichen Aufnahmepositionen angeord-net ist;

Fig. 2

einen Ausschnitt einer mittels der Bilderfassungseinrichtung in einer ersten Aufnahmeposition erfassten ersten Abbildung der Szene;

Fig. 3

einen Ausschnitt einer zweiten mittels der Bilderfassungseinrich-tung in einer von der ersten Aufnahmeposition verschiedenen weiteren Aufnahmeposition erfassten Abbildung der Szene;

Fig. 4

ein Koordinatensystem der Szene und ein Koordinatensystem der Bilderfassungseinrichtung mit einem Brillenglas;

Fig. 5

ein Strahlenmodell einer Brillenfassung bei Beobachten der Szene aus zwei unterschiedlichen Perspektiven;

Fig. 6

eine aus dem Strahlenmodell der Brillenfassung berechnete Brech-kraftverteilung;

Fig. 7

ein Flussdiagramm einer Ausgestaltung eines Verfahrens zum Vermessen eines linken und/oder rechten Brillenglases in einer Brillenfassung;

Fig. 8

ein Flussdiagramm einer weiteren Ausgestaltung eines Verfahrens zum Vermessen eines linken und/oder rechten Brillenglases in einer Brillenfassung;

Fig. 9

eine weitere Szene mit einer Brillenfassung und mit einer Bilderfas-sungseinrichtung, die in unterschiedlichen Aufnahmepositionen angeordnet ist;

Fig. 10

eine weitere Szene ohne die Brillenfassung mit der Bilderfassungseinrichtung;

Fig. 11

eine weitere Szene mit einer Brillenfassung und mit einer Bilderfassungseinrichtung, die in unterschiedlichen Aufnahmepositionen angeordnet ist;

Fig. 12

einen Ausschnitt der mittels der Bilderfassungseinrichtung in der ersten Aufnahmeposition erfassten Abbildung der Szene;

Fig. 13

eine weitere Szene ohne die Brillenfassung mit der Bilderfassungs-einrichtung; und

Fig. 14

einen Ausschnitt der mittels der Bilderfassungseinrichtung erfassten Abbildung der Szene ohne die Brillenfassung.

Show it:

1

a scene with a spectacle frame and with an image capturing device, which is arranged in different recording positions;

2

a section of a first image of the scene captured by the image capturing device in a first recording position;

3

a section of a second image of the scene captured by the image capture device in a further capture position that differs from the first capture position;

4

a coordinate system of the scene and a coordinate system of the image capturing device with a spectacle lens;

figure 5

a ray model of a spectacle frame when observing the scene from two different perspectives;

6

a refractive power distribution calculated from the ray model of the spectacle frame;

7

a flowchart of an embodiment of a method for measuring a left and/or right spectacle lens in a spectacle frame;

8

a flow chart of a further embodiment of a method for measuring a left and/or right spectacle lens in a spectacle frame;

9

another scene with a spectacle frame and with an image capturing device that is arranged in different recording positions;

10

another scene without the eyeglass frame with the image capturing device;

11

a further scene with a spectacle frame and with an image capturing device which is arranged in different recording positions;

12

a section of the image of the scene captured by the image capturing device in the first recording position;

13

another scene without the glasses frame with the image capturing device; and

14

a section of the image of the scene captured by the image capturing device without the spectacle frame.

the 1 shows as a scene 10 a table 12 with a tablecloth 14, on which a pair of glasses 16 with a frame 18 and with a left and right lens 20, 22 accommodated therein, in addition to further objects 24 in the form of a knife, a bottle, a cup and a Book and a cigar is arranged. The one in the 1 Scene 10 shown is time-invariant and contains characteristic points of a pattern of tablecloth 14 and objects 24 as structure points 26, which define a coordinate system 25 of scene 10, as well as characteristic points of spectacle frame 18 of spectacles 16.

In order to measure the local refractive power of the left and right spectacle lenses 20, 22 in the spectacles 16, the scene 10 is recorded by the camera 28 in an image acquisition device 30 designed as a smartphone in a large number of different recording positions 32, 34, 36, ... by a user holding the smartphone switched to video mode with one hand and moving it along a trajectory 38 . The user thus captures the scene 10 using the camera 28 of the image capturing device 30 from different perspectives. Image capture device 30 contains a computer unit 40 for processing the recordings of scene 10 captured by camera 28.

the 2 is a section 42 of a first image of the scene 10 with images 26 ′ of structure points 26 captured by the image capturing device 30 from a first recording position 32 3 is another detail 42 of a means of the image acquisition device 30 from one of the first recording position 32 different further recording position 36 captured first image of the scene 10 with images 26 'of structure points 26 shown.

When moving the image capture device 30 relative to the scene 10, as can be seen from FIG 2 and 3 results, a multiplicity of structure points 26 are each detected with an imaging beam path which passes through the first and/or the second spectacle lens 20, 22 in the spectacle frame 18 of the spectacles 16 or not. In addition, when the image capturing device 30 is displaced relative to the scene 10, images of the scene 10 are captured, which contain a section of the spectacle frame 18 that defines a coordinate system 44 of the spectacle frame 18.

the 4 shows the coordinate system 25 of the scene 10 and a coordinate system 46 of the image capture device 30 with a spectacle lens 20, 22. From the many recorded images of the scene 10, the computer unit 40 in the image capture device 30 calculates the coordinates of the structure points 26 of a pattern 27 using a SLAM algorithm in the scene by means of a ray model in a coordinate system 46 referenced to the image capturing device 30, which in turn is referenced to the coordinate system 25 of the scene 10 and the coordinate system 44 of the spectacle frame 18 of the spectacles 16.

the figure 5 shows a beam model of the glasses 16 with imaging beam paths guided into the camera 28 of the image capturing device 30 with main rays 53, 53' for structure points 26 when the scene 10 is captured from two different recording positions 32, 34. Such a ray model not only requires knowledge of the positions of the imaging device 30, but also requires a three-dimensional model for the scene 10 and knowledge of the position of the in the 1 glasses 16 shown in the scene 10 and also the information ahead as to which structural points 26 in of the scene 10 the image capturing device 30 captures through the left spectacle lens 20 or the right spectacle lens 22 of the spectacles 16 .

eines in der Kamera 28 der Bilderfassungseinrichtung 30 abgebildeten Strukturpunkts 26 eines Musters 27 der Szene 10 wird bei einem bekannten Kamerakalibrierungsoperator K̅ ein in die Kameraoptik einfallender Hauptstrahl eines Abbildungsstrahlengangs in Form eines dreidimensionalen Vektors im Koordinatensystem 46 der Bilderfassungseinrichtung der Kamera 28 $${\overrightarrow{r}}_0={\bar{K}}^{-1}\cdot C$$

mit $$\bar{K}=\left(\begin{array}{ccc}{K}_{11}& K_{12}& K_{13}\\ K_{21}& K_{22}& K_{23}\\ K_{31}& K_{32}& K_{33}\end{array}\right)$$

bestimmt. Aus der bekannten räumlichen Position der Kamera 28 und deren räumlichen Lage im Koordinatensystem 25 können der Translationsoperator $$\overrightarrow{T}$$

und der Rotationsoperator $$\bar{R}=\left(\begin{array}{ccc}{R}_{11}& R_{12}& R_{13}\\ R_{21}& R_{22}& R_{23}\\ R_{31}& R_{32}& R_{33}\end{array}\right)$$

mit $$\mathit{det}\bar{R}=1$$

bestimmt werden. Aus diesen wird r ₀ durch Lineartransformation $${\overrightarrow{r}}_{\mathit{Szene}}={\bar{R}}^T\cdot \left({\overrightarrow{r}}_0-\bar{T}\right)$$

aus dem Koordinatensystem 46 der Bilderfassungseinrichtung der Kamera 28 durch eine dem Rotationsoperator R̅ entsprechende Drehung in das Koordinatensystem 25' und dann durch eine dem Translationsoperator T entsprechende Translation in das Koordinatensystem 25 der Szene 10 überführt.To that in the figure 5 To calculate the ray model shown, refer to FIG 4 proceeded as follows:
From the pixel coordinate in homogeneous coordinates $$C=\left(\begin{array}{c}{C}_x\\ C_y\\ 1\end{array}\right)$$

of a structure point 26 of a pattern 27 of the scene 10 that is imaged in the camera 28 of the image capturing device 30, with a known camera calibration operator K̅ , a principal ray of an imaging beam path incident on the camera optics is in the form of a three-dimensional vector in the coordinate system 46 of the image capturing device of the camera 28 $${\overrightarrow{\mathrm{right}}}_0={\bar{K}}^{-1}\cdot C$$

With $$\bar{K}=\left(\begin{array}{ccc}{K}_{11}& K_{12}& K_{13}\\ K_{21}& K_{22}& K_{23}\\ K_{31}& K_{32}& K_{33}\end{array}\right)$$

definitely. From the known spatial position of the camera 28 and its spatial location in the coordinate system 25, the translation operator $$\overrightarrow{T}$$

and the rotation operator $$\bar{R}=\left(\begin{array}{ccc}{R}_{11}& R_{12}& R_{13}\\ R_{21}& R_{22}& R_{23}\\ R_{31}& R_{32}& R_{33}\end{array}\right)$$

With $$\mathit{de}\bar{R}=1$$

to be determined. These become right ₀ by linear transformation $${\overrightarrow{\mathrm{right}}}_{\mathit{scene}}={\bar{R}}^T\cdot \left({\overrightarrow{\mathrm{<figure-callout\; id="0"\; label="right\; \to "\; filenames="imgf0004.png"\; state="\{\{state\}\}">right</figure-callout>}}}_0-\bar{T}\right)$$

from the coordinate system 46 of the image acquisition device of the camera 28 by a rotation corresponding to the rotation operator R̅ into the coordinate system 25' and then by a rotation operator T corresponding translation into the coordinate system 25 of the scene 10 is transferred.

By detecting and tracking stationary, time-invariant structure points 26, whose imaging beam paths do not pass through the spectacle lenses, over several recordings at different recording positions 32, 34, 36 using feature matching algorithms, for each of these structure points 26 from the intrinsic parameters of the image capturing device and the location and position of an image capturing device at the time of capturing an image, its location in the scene 10 in the coordinate system 46 of the image capturing device 30 can thus be inferred.

A principal ray 53 , 53 ′, which passes through a spectacle lens 20 , 22 of the spectacles 16 , is then calculated from each imaged structure point 26 in accordance with the position of the image acquisition device 30 . From this and from the 3D coordinate of the point, a ray model then results, which reflects different viewing conditions of the same pair of glasses 16 in the same scene 10 and the imaging rays that are deflected and the different Layers and positions of an image acquisition device correspond, describes.

About a so-called inverse approach, as z. B. in the publication of KN Kutukalos and E. Steger, A Theory of Refractive and specular 3D Shape by Light-Path Triangulation, International Journals of Computer Vision, 2008, Volume 76, Issue 1, Pages 13-29 , is described, to which reference is hereby made in full and the disclosure content of which is included in the description of this invention, it is then possible to use this data set to determine both the position and the shape and position as well as the refractive index of the material of the left and right spectacle lens 20 , 22 in the spectacle frame 18 of the spectacles 16 and thus also their optical effect for a spectacle wearer.

An inverse approach is a reversal of the so-called forward calculation, in which the course of light rays through an optical system consisting of known optical interfaces and known refractive indices between the interfaces is calculated in an optical ray tracing, also known as ray tracing. Provided that the interfaces, their normals and the refractive indices are known, it is then possible to calculate each light ray through the system unambiguously. In the case of the inverse approach, an optical interface or a refractive index is sought that matches a given number of light rays. In order to determine an error size, the forward calculation is carried out using the area determined using the inverse approach, and a comparison of beam points in front of and/or behind the respective interface is then made. By varying the area to be determined, the error size is then minimized in a targeted manner using an optimization process. As an alternative to pure optimization methods, which can determine the minimum of an error function through parameter variations, it is also possible to use so-called light path triangulation methods, which are also used in combination with an optimization method will. Such methods are z. B. in the above-mentioned publication " KN Kutukalos and E. Steger, A Theory of Refractive and specular 3D Shape by Light-Path Triangulation, University of Toronto " described.

If their shape and refractive index are known, the dioptric power of the spectacle lenses can be calculated in particular by forward calculation of beams of rays. The vertex power of a spectacle lens can e.g. B. be determined by a parallel bundle of rays whose diameter is about 5 mm and thus corresponds to the size of the pupil of the eye, is propagated through the lens such that its principal ray, i. H. whose optical axis leaves the lens vertically on the eye side. The value of the vertex refractive index is then the reciprocal of the distance from the lens surface from which the principal ray emerges to the point of the smallest ray waist or extension of the ray bundle.

In the case of spectacle lenses comprising at least one toric effect, the direction-dependent expansion of the beam of rays has two minima. The distance between these two minima and the surface of the spectacle lens describes the effect of the two principal sections. The difference between these two principal sections describes the cylindrical effect of the spectacle lens. The entire deflection of the main beam by the lens is to be considered as the prismatic effect of the lens at the respective point.

The so-called intrinsic camera calibration operator K - is used for the conversion of pixel coordinates C of the camera 28 in the image acquisition device 30 to the ray vector of an imaging beam path . The camera calibration operator K̅ can e.g. B. from a recording of a special calibration pattern, z. B. a checkerboard pattern or a dot pattern can be determined by means of the image acquisition device. As an alternative to this, it is also possible by evaluating a large number of recordings or images to determine the intrinsic camera calibration operator K̅ of the scene 10 directly from recordings or images of the scene 10, which are based on different recording positions 32, 34, 36.

In the 6 is a graph 52 for a based on in the figure 5 shown beam model of the glasses 16 calculated distribution of the refractive power k (x, y) for the left and right glasses 20, 22 to see.

the 7 is a flowchart 54 of the above-described method for measuring a left and/or right spectacle lens 20, 22 in spectacles 16.

In a first step S1, at least a first image of a scene 10 with a large number of structure points 26 and with a left and/or a right spectacle lens 20, 22 in a pair of spectacles 16 and with a section defining a coordinate system 44 of the spectacle frame 18 of the spectacle 16 is created of the spectacle frame 18 of the spectacles 16 is detected by means of an image acquisition device 30 with an imaging beam path for structure points 26 which passes through the first and/or the second spectacle lens 20, 22 of the spectacles 16.

In a step S2 following step S1, at least two further images of the scene 10 without the first and/or the second spectacle lens 20, 22 of the spectacles 16 with the structure points 26 imaged in the first image are then captured by the image capturing device 30.

In a step S3, the coordinates of the stationary, time-invariant structural points 26 are then calculated in the coordinate system 25 of the scene 10 referenced to the coordinate system 46 of the image acquisition device 30 in the different recording positions from the at least two other images of the scene 10 by means of image evaluation.

In a step S4 following step S3, the refractive power distribution k(x, y) is then determined for at least one section of the left spectacle lens 20 in the coordinate system 44 of the spectacle frame 18 referenced to the coordinate system 25 of the scene 10 and/or the refractive power distribution is determined k(x, y) for at least one section of the right spectacle lens 22 in a coordinate system 25 of the scene 10 referenced to the coordinate system 44 of the spectacle frame 18 from the coordinates of the stationary, time-invariant structure points 26 and the image of the structure points 26 in the at least one first image of scene 10.

the 8 shows a flowchart 54 for an alternative method to the above-described method for measuring a left and/or right spectacle lens 20, 22 in a pair of spectacles 16, which is described below with reference to FIG Figures 9 to 12 is described.

Again, in a first step S1, as in the 9 can be seen, a sequence of first images of a time-invariant scene 10 with a multiplicity of structure points 26 and with a left and/or a right spectacle lens 20, 22 in a spectacle 16 together with a section of the spectacle frame 18, which is a in the 4 shown coordinate system 44 of the spectacle frame 18 is defined.

Like in the 9 As can be seen, images of scene 10 are captured using imaging beam paths for structure points 26, which at least partially penetrate the first and/or the second spectacle lens 20, 22 of the spectacle 16 and on the first and/or the second spectacle lens 20, 22 the glasses 16 are at least partially passed.

In a step S1 following step S2, as in FIG 10 to see a sequence of further images of the scene 10 with stationary, time-invariant structure points 26, but recorded without the glasses 16. to it should be noted that step S2 can also precede step S1 or take place simultaneously with it.

In a step S3, the coordinate system 25 of the scene 10 is referenced to the coordinate system 44 of the spectacle frame 18 and then the coordinates of the structure points 26 in the coordinate system 25 of the scene 10 referenced to the coordinate system 46 of the image acquisition device 30 in the different recording positions from the at least another image of the scene 10 is calculated by means of image analysis.

Then, in a step S4, the refractive power distribution k(x,y) is determined for at least one section of the left spectacle lens 20 in the coordinate system 44 of the spectacle frame 18 referenced to the coordinate system 25 of the scene 10 and/or the refractive power distribution k(x,y ) for at least one section of the right spectacle lens 22 in the coordinate system 44 of the spectacle frame 18 from the coordinates of the structural points 26 and the image of the structural points 26 in the at least one first image of the scene 10.

As the Figures 11 to 14 show, the measurement of a left and/or right spectacle lens 20, 22 in a spectacle frame 18 is also possible by capturing images of a scene 10 in which a spectacle wearer with spectacles and without spectacles is located. As in the 11 can be seen, a sequence of first images of a time-invariant scene 10 with a large number of structure points 26 and with a left and/or a right spectacle lens 20, 22 in a spectacle frame 18 together with a section of the spectacle frame 18 is captured by means of an image acquisition device 30, which Coordinate system 44 of the spectacle frame 18 is defined. As the 12 shows, the capturing of images of the scene 10 takes place with imaging beam paths for structure points 26, which at least partially penetrate the first and/or the second lens 20, 22 of the glasses 16 and on the first and/or the second spectacle lens 20, 22 of the spectacles 16 are guided at least partially past.

Then, as in the 13 and 14 to see a sequence of further images of the scene 10 with structure points 26, but recorded without the glasses 16. The coordinates of structural points 26 in a coordinate system 25 of scene 10 referenced to coordinate system 46 of image acquisition device 30 at different recording positions are then calculated from the at least one further image of scene 10 by means of image evaluation, and coordinate system 25 of scene 10 is assigned to the Coordinate system 44 of the spectacle frame 18 is referenced. Then the refractive power distribution k(x,y) for at least a section of the left spectacle lens 20 in the coordinate system 44 of the spectacle frame 18 is determined and/or the refractive power distribution k(x,y) for at least a section of the right spectacle lens 22 in the coordinate system 44 of the spectacle frame 18 is determined from the coordinates of the structure points 26 and the image of the structure points 26 in the at least one first image of the scene 10 .

Because there are structure points 26 in scene 10, which are in the 11 and 13 shown, due to movements of the spectacle wearer, the computer unit of the image acquisition device 30 contains a program routine here, by means of which the position of the structural points 26 can be determined by evaluating neighboring relationships, in particular distances between the structural points 26 in the scene 10, in a coordinate system 44 coordinate system 25 of scene 10 referenced by eyeglass frame 18 is calculated.

Provision can be made for the neighborhood relationships between structure points 26 in scene 10 to be evaluated in order to detect a displacement of structure points 26 in a coordinate system 25 of scene 10 and the coordinates of structure points 26 displaced in a scene 10 not to be taken into account when determining the refractive power distribution for at least a section of the right spectacle lens 22 and the left spectacle lens 20 in the coordinate system 44 of the spectacle frame 18, so that movements of structural points 26 in the scene 10 can determine the measurement result for the local refractive power of the left and right spectacle lens 20, 22 do not falsify.

In summary, the following can be stated in particular: The invention relates to a method for measuring the local refractive power or the refractive power distribution of a left and/or a right spectacle lens 20, 22 in a spectacle frame 18. At least a first image of a scene 10 with at least one structural point 26 and with a left and/or a right spectacle lens 20, 22 in a spectacle frame 18 by means of an image acquisition device 30 from at least a first recording position 32 with at least one imaging beam path for structural points 26, which captures the first and/or the second spectacle lens 20, 22 in the spectacle frame 18 interspersed. At least two further images of scene 10 without the first and/or second spectacle lens 20, 22 of spectacle frame 18 or without the spectacle frame containing the left and/or right spectacle lens with the structure points 26 shown in the first image are captured by means of image capture device 30 from at least two different recording positions 32, 34, 36, one of which can be identical to the first recording position, and the coordinates of structure points 26 in a coordinate system 25 are calculated from the at least two other images of scene 10 by means of image evaluation, or it at least two further images of the scene 10 with the left and/or the right spectacle lens 20, 22 are created by means of an image acquisition device 30 from at least two further image positions different from the first image position with at least one imaging beam path for the structure points 26 e r detects the first and / or the second lens 20, 22 of the spectacle frame 18 does not penetrate, to then a refractive power distribution k (x, y) for at least a portion of the left lens 20 in a coordinate system 25 of the scene 10 referenced to the coordinate system 44 of the spectacle frame 18 and/or a refractive power distribution k(x,y) for at least one section of the right spectacle lens 22 in a coordinate system 25 from the coordinates of the structural points 26 and the image of the structural points 26 in the at least one first image of the scene 10 to be determined.

Claims (15)

1. Method for measuring the local refractive power of a left and/or a right spectacle lens (20, 22) in a spectacle frame (18),

   including a step of capturing at least one first image representation of a scene (10) with at least one structure point (26) and with a left and/or a right spectacle lens (20, 22) in the spectacle frame (18) by means of at least one image capture device (30) from at least one first recording position (32) with at least an imaging beam path for the at least one structure point (26), said imaging beam path passing through the left or the right spectacle lens (20, 22),

   characterized

   in that at least two further image representations of the scene (10) with the at least one structure point (26) imaged in the at least one first image representation are captured by means of the at least one image capture device (30),

   - without the left and/or the right spectacle lens (20, 22) of the spectacle frame (18) being captured from at least two different recording positions (32, 34, 36), one of which can be identical to the first recording position (32), or

   - with the left and/or the right spectacle lens (20, 22) in the spectacle frame (18) being captured from at least two different further recording positions (34, 36), which differ from the first recording position (32), wherein the respective imaging beam path for the at least one structure point (26) captured in the at least one first image representation does not pass through the left and the right spectacle lens (20, 22) of the spectacle frame (18);

   in that in the step of capturing the at least one first image representation of the scene (10) a section of the spectacle frame (18) of the pair of spectacles (16) is captured, said section defining a coordinate system (44) of the spectacle frame (18) of the pair of spectacles (16);

   in that the coordinates of the at least one structure point (26) are calculated in a coordinate system (25), which is referenced to the coordinate system (44) of the spectacle frame (18), from the at least two further image representations of the scene (10) by means of an image evaluation;

   in that the absolute position, relative position and boundary of the spectacle frame (18) are calculated by means of an image evaluation using an object recognition method; and

   in that a local refractive power k(x,y) is determined for at least one section of the left spectacle lens (20) and/or for at least one section of the right spectacle lens (22) by virtue of

   a ray model with imaging beam paths which pass through the left and/or right spectacle lens (20, 22) and which reach the at least one structure point (26) after refraction by the left and/or right spectacle lens (20, 22) being determined from the coordinates of the at least one structure point (26) and a chief ray (53) which passes through the left or right spectacle lens and which is calculated for the image of the at least one structure point (26) in the at least one first image representation of the scene (10) corresponding to the respective position of the image capture device (18).
2. Method for measuring the local refractive power of a left and/or a right spectacle lens (20, 22) in a spectacle frame (18),

   including a step of capturing at least two first image representations of a scene (10) with at least one structure point (26) and with a left and/or a right spectacle lens (20, 22) in the spectacle frame (18) by means of at least one image capture device (30) from at least two recording positions (32, 34, 36) with in each case at least an imaging beam path for the at least one structure point (26), said imaging beam path passing through the left or the right spectacle lens (20, 22),

   characterized

   in that at least two further image representations of the scene (10) with the at least one structure point (26) imaged in the at least two first image representations are captured by means of the at least one image capture device (30) from at least two different recording positions (32, 34, 36) without the spectacle frame (18) containing the left and/or the right spectacle lens (20, 22);

   in that in the step of capturing the at least two first image representations of the scene (10) a section of the spectacle frame (18) of the pair of spectacles (16) is captured, said section defining a coordinate system (44) of the spectacle frame (18) of the pair of spectacles (16);

   in that the coordinates of the at least one structure point (26) are calculated in a coordinate system (25), which is referenced to the coordinate system (44) of the spectacle frame (18), from the at least two further image representations of the scene (10) by means of an image evaluation;

   in that the absolute position, relative position and boundary of the spectacle frame (18) are calculated by means of an image evaluation using an object recognition method; and

   in that a local refractive power k(x,y) is determined for at least one section of the left spectacle lens (20) and/or for at least one section of the right spectacle lens (22) by virtue of

   a ray model with imaging beam paths which pass through the left and/or right spectacle lens (20, 22) and which reach the at least one structure point (26) after refraction by the left and/or right spectacle lens (20, 22) being determined from the coordinates of the at least one structure point (26) and a chief ray (53) which passes through the left or right spectacle lens and which is calculated for the image of the at least one structure point (26) in at least one of the first image representations of the scene (10) corresponding to the respective position of the image capture device (18).
3. Method according to Claim 1 or 2, characterized by capturing a multiplicity of first image representations of the scene (10) and a multiplicity of further image representations of the scene (10), wherein the coordinates of the at least one structure point (26) in the coordinate system (25) which is referenced to the coordinate system (44) of the spectacle frame (18) are calculated from the multiplicity of further image representations of the scene (10).
4. Method according to any one of Claims 1 to 3, characterized in that the scene (10) contains a left eye (48) and/or right eye (50) of a spectacle wearer of the spectacle frame (18).
5. Method according to Claim 4, characterized in that the image capture device (30) is used to capture a multiplicity of image representations of the scene (10) with a displacement of the image capture device (30), wherein the left eye (48) and/or the right eye (50) of the wearer of the spectacle frame (18) gazes at the displaced image capture device (30) and viewing beam paths for different viewing directions of the left eye (48) and/or right eye (50) of the wearer of the spectacle frame (18) through the left spectacle lens (20) and/or the right spectacle lens (22) of the spectacle frame (18) are calculated from the multiplicity of image representations of the scene (10) captured in the process and a local refractive power k(x,y) of the left spectacle lens (20) and/or the right spectacle lens (22) is determined for each viewing direction therethrough.
6. Method according to any one of Claims 1 to 5, characterized in that a SLAM algorithm is used to calculate intrinsic parameters of the at least one image capture device (30).
7. Method according to Claim 6, characterized by intrinsic parameters from the group of focal length, image centre, shearing parameters, scaling parameters, distortion parameters.
8. Method according to any one of Claims 1 to 7, characterized in that a SLAM algorithm is used to calculate the coordinates of the at least one structure point (26) and/or the recording positions (32, 34, 36) of the at least one image capture device (30) in the coordinate system (25), which is referenced to the coordinate system (44) of the spectacle frame (18); and/or in that the coordinates of at least some of the structure points (26) in the scene (10) are invariant; and/or in that the coordinates of the at least one structure point (26) are calculated in a coordinate system (25), which is referenced to the coordinate system (44) of the spectacle frame (18), by evaluating displacements between the image representations of the structure points (26) in the scene (10) from different recording positions (32, 34, 36).
9. Method according to any one of Claims 1 to 8, characterized in that a displacement of structure points (26) in a coordinate system (25) is recognized by evaluating the proximity relations between the structure points (26) in the scene (10), and the coordinates of structure points (26) displaced in a scene (10) are not taken into account when determining the refractive power distribution k(x,y) for at least one section of the right spectacle lens (22) and/or the left spectacle lens (20).
10. Method for measuring the refractive power distribution k(x,y) of a left and/or a right spectacle lens (20, 22) in a spectacle frame (18), wherein a local refractive power of the left and/or right spectacle lens (20, 22) is measured according to any one of Claims 1 to 9 at a plurality of different locations on the left and/or right spectacle lens (20, 22).
11. Computer program product comprising a computer program having program code for carrying out all method steps which are specified in any one of Claims 1 to 10 when the computer program is loaded on a computer unit (40) and/or executed on a computer unit (40) .
12. Apparatus for measuring the local refractive power of a left and/or a right spectacle lens (20, 22) in a spectacle frame (18), comprising an image capture device (30) and comprising a computer unit (40), loaded onto which is a computer program with program code for carrying out all method steps specified in any one of Claims 1 to 9, or for measuring the refractive power distribution of a left and/or a right spectacle lens (20, 22) in a spectacle frame (18), comprising an image capture device (30) and comprising a computer unit (40), loaded onto which is a computer program with program code for carrying out all method steps specified in Claim 10.
13. Apparatus according to Claim 12, embodied as a smartphone or as a tablet computer or as a camera (28) .
14. Computer-readable data medium, on which the computer program product according to Claim 11 is stored.
15. Data medium signal, which transmits the computer program according to Claim 11.

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